Liz Garbus was thrilled to learn that her documentary, "What Happened, Miss Simone?" had been nominated for an Academy Award for Best Documentary Feature.

But, she added, it's even more special given how much she knows it would have meant to her subject, the legendary singer Nina Simone.

Winning on Sunday would be a boon to Simone's legacy, Garbus noted, especially because the piano prodigy never won a Grammy, despite garnering multiple nominations.

"The industry will applaud work, but only so far. This is a recurring thing. People can go so far but not all the way, and right before she died, they gave her a Hall of Fame award, but it was too little, too late," she told ABC News. "[An Oscar] would show that these stories can go all the way."

Garbus, who directed and produced the movie, first came to the project when she met Simone's daughter Lisa Simone Kelly, who had been searching for someone to make a film about her mother. Garbus was a good fit: Her documentary, "The Farm: Angola, USA," which focuses on a maximum-security prison in Angola, Louisiana, was nominated for an Oscar. She also has experience making movies about celebrities, including "Bobby Fischer Against the World" and "Love, Marilyn," a film about Marilyn Monroe.

Over the course of production, Garbus pored over hours of audio interviews that Simone had given to the collaborator of her autobiography and read diaries provided to her by Kelly. She also conducted interviews with people who intimately knew the singer, including Attallah and Ilyasah Shabazz, daughters of Malcolm X. and Betty Shabazz, who grew up next door to Simone, and Simone's longtime musical director, Al Shackman.

"It was incredible. It took a lot of convincing for a lot of these folks. People felt like Nina was very, very easy to get wrong. She was complicated," Garbus explained. "You can go too far and destroy somebody. So people were very protective and didn't know how to talk about her in some ways, but they wanted to honor her and be truthful."

But it's Kelly's commentary throughout the Netflix documentary that most exemplifies how complex Simone's life was. As a girl who dreamed of becoming a concert pianist, Simone transformed into a politically-minded, fiery musician who, according to her diaries, was in an abusive marriage with Kelly's father, Andy Stroud. And while Kelly recalled having a happy childhood with her mother in Mount Vernon, New York, she also also delved into the toll that fame and political pressures put on her mother. Simone was tortured, Kelly said, and at times, behaved abusively.

"To make a movie about Nina Simone and not go there psychologically would not be a film that people who are interested in her would find satisfying," Garbus said. "Her work can still be in the canon. Her work can be the brilliant, extraordinary, groundbreaking work it was while the human being at the center is in pain and struggling and making decisions that we don't want her to make. She can be canonized but that does not mean she needs to be idealized."

Though Garbus admitted she was nervous to show Kelly the film, she was touched by her reaction.

"I got a beautiful email from Lisa: 'I told mommy when she died I'd have her back, and now my job is done. I don't need to explain anymore,'" Garbus recalled. "For her, it was a way of being able to move on, I think."

On Sunday, Garbus will attend the show with Kelly and Kelly's daughter, Re'Anna. Whether the documentary takes home the award or not, she noted that everyone involved with the project is "thrilled to be where we are." (Other nominees include "Amy," about the life of Amy Winehouse, "The Look of Silence," a profile of an optician whose brother was murdered during the Indonesian genocide, "Winter on Fire: Ukraine's Fight for Freedom," an examination of the civil rights movement in the Ukraine, and "Cartel Land," the story of vigilantes protesting the Mexican drug cartels.) They're also happy that so many people are learning more about Simone's life, and the filmmaker noted, Simone would be too.

"She would definitely be concerned with what her legacy was. She was called the High Priestess of Soul and she felt like she deserved that type of respect," Garbus said. "I think it would be false to say she didn’t care about such things. We know she would!"

The 88th Academy Awards will air at 7 p.m. ET on Feb. 28, 2016 on ABC.